The invention relates to vacuum toilet systems, particularly for use on vehicles such as boats, planes, trains, recreational vehicles, and the like, and to component parts for such systems. Vacuum toilet systems, such as those sold for many years under the "Vacu-Flush".RTM. trademark have had many practical advantages including being able to flush without using large amounts of precious clean water, low energy use per flush, excellent system flexibility, and the avoidance of using macerators or other accessory pieces of equipment to break up the sewage. While the Vacu-Flush.RTM. system has been very commercially successful, there are some aspects thereof that can be improved upon as far of ease of construction, optimization of functionality, and minimization of the number of components is concerned. According to the present invention a vacuum toilet system, and various components thereof, are provided which retain the numerous advantages of the Vacu-Flush.RTM. system, yet improve upon it.
One important element of a vacuum toilet is a flexible seal between the bowl and the vacuum source which cooperates with the movable valve element. In the past such seals have been constructed solely of synthetic rubber or like elastomeric material, or have been formed of two different materials (such as in U.S. Pat. No. 3,599,248) including a ring of material such as polytetraflouroethylene having a low coefficient of friction and inherent lubricity, which is bonded to the synthetic rubber major portion of the seal. If a sealing element solely of synthetic rubber is utilized there is not enough lubricity between the movable valve element and the seal, and where a separate Teflon.RTM. ring is utilized there are difficulties in construction and bonding between the components. Also, in view of the fact that such seals are preferably used in association with china (ceramic) bowls, the inherent irregularities in the china bowl may cause problems in effecting an appropriate seal between the bowl and the sealing material itself.
According to the invention these difficulties have been overcome by molding the sealing element in a particular way. The sealing element includes an annular one-piece element of resilient material having a body and first and second radially spaced concentric rings upstanding from the body. The radially spaced upstanding rings provide effective sealing with the ceramic bowl, despite the high degree of irregularity thereof. The body is of a first material, preferably synthetic rubber, while an inner flap portion is integral with the body but is of a second material having greater lubricity, such as synthetic rubber blended with polytetraflouroethylene. When providing the sealing element as an integral structure the durometer of the entire seal can be the same throughout (e.g. about 55-65), with desired results in achieving proper sealing over long periods of time.
In past vacuum toilet systems there have been many situations in which it has been desirable to pump the sewage to a holding or treatment tank, and then when the holding or treatment tank is full to discharge the sewage therefrom. This has typically required the utilization of two pumps. According to the invention, however, the necessity for two pumps has been eliminated, and by placing three-way valves on opposite sides of a single pump, the holding tank may be either filled or emptied utilizing a single pump. Also in conventional systems, having multiple heads, if a pump broke down all of the heads associated with that pump would be rendered inoperable. According to the invention, conduits associated with multiple heads are interconnected in such a way that if one pump breaks down another pump associated with another set of heads may be utilized to serve both sets of heads for a short period of time until repairs can be effected.
In the successful Vacu-Flush.RTM. vacuum toilet system, maceration has been achieved without the necessity of mechanical macerating elements or the like. It has always been thought that the majority of maceration was provided at an orifice which is provided several inches below the valve on the opposite side from the toilet bowl. However, upon further study of the mechanisms involved, it has now been determined that the majority of the maceration takes place when the solid sewage material is first exposed to the vacuum source by initial "cracking open" of the valve. In view of this, it becomes desirable to place the orifice means (which preferably comprises a knife-edge orifice), at the bottom of the funnel leading to the orifice means, directly below the portion of the valve where the initial passageway is formed when the valve is opened. In this way, the waste need undergo minimum changes in direction, which should accentuate the fragmenting action that is provided. Variable shapes of the funnel and orifice may be provided to further enhance this action, and valve opening can be provided by a reciprocal movable valve element or a conventional hemispherical ball rotating valve element.
Conventional vacuum toilets--since they use a small volume of water--typically are flushed with fresh water from a storage facility on the vessel or vehicle rather than utilizing sea water or polluted water. This has a number of advantages, of course, in insuring longevity and proper operation of the system. However, when supplying fresh water to a vacuum system, it is necessary to ensure that a siphoning effect does not occur during the flushing of the toilet. This is typically accomplished utilizing an anti-siphon valve or "vacuum-breaker" mounted on the bowl. While conventional anti-siphon valves have performed the desired functions, they normally have been relatively complicated in construction the bodies being relatively difficult to mold and containing significant amounts of plastic.
According to the present invention, an anti-siphon valve is provided which has a number of advantages of simplicity of construction and operation and minimization of material, compared to conventional vacuum-breakers utilized in vacuum toilet systems and additionally allows for ready connection of a hand operated nozzle spray head so that the bowl may be rinsed in particular portions thereof with small amounts of water rather than relying merely upon where the water is directed by the conventional attachment of the anti-siphon valve to the toilet bowl.
In conventional vacuum toilets, the connection between the orifice of the bottom of the funnel and a conduit leading to the vacuum tank provides for rather limited flexibility. However, according to the invention, a collar can be provided around the knife edge orifice at the bottom of the funnel, the collar surrounding the orifice, and the collar providing a female connection for cooperation with a wide variety of different conventional connectors, including rigid one and one half inch pipe, one and one half inch inside diameter hose, or Ls for connection to hose or pipe.
The vacuum tank in conventional vacuum toilet systems has had a number of practical difficulties. The ports extending to and from the tank are of widely different construction, minimizing the flexibility of connection of various components to it. Also, the tank has been mounted utilizing a mounting base and clamping strap system that is less than desirable, and because that system that is less than desirable, and because of the cooperation of the outlet from the tank and the tank itself, liquid (which includes sewage particles) can collect at the bottom of the tank. The provision of sewage constantly in the tank is undesirable for many reasons.
According to the invention, however, a vacuum tank is provided which eliminates these drawbacks. The tank is preferably formed by blow molding plastic so that it has no seams. It is constructed so that it has universal ports so that any of a number of different elements can be connected to any of the ports, providing maximum flexibility for installation of the system. At least one of the ports is constructed so that it has as a portion thereof as a continuation of the side wall of the circular-cross section of the tank, so that no accumulation of sewage within the tank ever occurs if that port is used as the outlet port. Further, ribs are integrally molded on the outside of the tank extending in the direction of elongation of the tank, the ribs including a plurality of through extending openings which are substantially tangential to the tank and adapted to directly connect to a bracket for bolting of the tank to the bracket. By providing four equally circumferentially spaced longitudinal ribs on the tank maximum flexibility in the mounting of the tank and orientation of the various ports is provided.
One conventional component that is mounted to the vacuum tank is the vacuum switch, which is responsive to the degree of vacuum in the tank and controls the vacuum pump when the level of vacuum drops (i.e. after a "flush" of a toilet associated with the tank). An electrical switch is typically mounted to the tank utilizing a plug adaptor and supporting mount, however, those components have usually required the utilization of stainless steel screws and an O-ring. The stainless steel screws were necessary since the plug adaptor and the switch support were connected together from the interior of the vacuum tank. According to the invention, a plug adaptor and a vacuum switch support mount are provided that cooperate in such a way that the screws may be provided into blind hole from the exterior of the vacuum tank so that stainless steel screws need not be utilized, and the base of the support mount is constructed in such a way that the O-ring is eliminated.
A conventional pump utilized in prior vacuum toilet systems is of the type such as in U.S. Pat. Nos. 3,529,908, 3,597,516, 3,714,536, 3,774,461. Such a pump is self-priming and handles solids up to one-half an inch, and contains dual check valves and a bellows associated with the movable pump element (piston). While such a pump is ideally suited for vacuum toilet systems, it has one operational drawback in that paper, from the toilet paper utilized with the system, tends to pack around the bellows and breaks down ultimately limiting the length of travel of the movable pump element and causing significantly decreased operational efficiency. This is avoided according the present invention by utilizing a rolling diaphragm pump instead of a bellows pump.
Further, the components of the conventional vacuum pump are relatively expensive and the expense of such a pump is significantly reduced according the invention by utilizing a plastic stem which has pegs extending from it that are staked or ultrasonically welded to a movable valve element. Further, a powdered metal crank arm is provided for transferring the motive force from the pump and gear reducer to the stem for reciprocating the movable valve element. The powdered metal crank arm can--in addition to being less expensive than a conventional solid metal crank arm--provide a fail-safe mechanism, which will fail before other components of the motor crank or pump system which are more expensive to replace, such as a gear reducer, or motor itself.
The vacuum toilet system, and components thereof, according to the invention have numerous advantages over the prior art while retaining the desirable features of the commercially successful prior "Vacu-Flush".RTM. system. This and other objects of the invention will be become clear from an inspection of the detailed description of the invention and from the appended claims.